Although early theorists (Cooley, 1902; Mead, 1934) speculated about how people draw inferences from the information supplied by others, the question of how self-relevant knowledge is combined to form one's self- concept has received little attention. Recent work on self-concept has mainly focused on the implications of already-developed self-relevant knowledge but not on how one forms conceptions about the self. The current work attempts to fill this gap in our knowledge, while exploring the implications of self-concept formation. The current work draws on the on-line vs. memory-based (Hastie & Park, 1986) processing distinction, which has been used to understand how people form impressions about individual and group social targets (McConnell, Sherman, & Hamilton, 1994b, in press). It is proposed that when people have resources and interest in processing self-relevant information in important behavioral domains, on-line self-concepts result. Conversely, in situations where people do not possess processing resources or interest in self-relevant abilities, or perceive the behavioral domain as relatively unimportant, memory-based self-concepts result. These studies (two preliminary, five proposed) test conditions under which memory-based vs. on-line self-concepts are produced. In addition to suggesting a process account for how self-concepts are formed, it is predicted that the way in which one forms a self-concept (memory-based vs. on-line) has meaningful implications. Those who form on-line (instead of memory-based) self- concepts will be especially influenced by early feedback, hold more stable and resilient self-concepts, and not be prone to certain biases (e.g., illusory correlations) in their self-concepts. Each study (preliminary and proposed) tests the consequences of how one forms self-concepts. Thus, the current work provides a process account for how self-concepts are formed. Moreover, it predicts that self-concepts will be formed differently based on certain antecedent conditions. These differences, in turn, will have important implications for the nature of the self-concept that is formed. Although this work posits that self-concept formation shares much in common with perception for other social targets (e.g., individuals, groups), it also predicts asymmetries for the self (relative to other social target types) based on unique motives that are associated with the self (e.g., self-enhancement). Because self-concepts have important implications (e.g., behavior, personal outlook, social comparison, and experience of emotion) for social functioning, an understanding of how self-concepts are formed, and the consequences of forming them, is important.